/*
 * Copyright 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

@file:JvmName("AppCompatTheme")
@file:Suppress("DEPRECATION")

package com.google.accompanist.themeadapter.appcompat

import android.content.Context
import androidx.compose.material.Colors
import androidx.compose.material.LocalContentColor
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Shapes
import androidx.compose.material.Typography
import androidx.compose.material.darkColors
import androidx.compose.material.lightColors
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.remember
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.core.content.res.use
import com.google.accompanist.themeadapter.core.parseColor
import com.google.accompanist.themeadapter.core.parseFontFamily

/**
 * This function creates the components of a [MaterialTheme], synthesizing a material theme
 * from values in the [context]'s `Theme.AppCompat` theme.
 *
 * If you are using [Material Design Components](https://material.io/develop/android/)
 * in your app, you should use the
 * [MDC Compose Theme Adapter](https://github.com/material-components/material-components-android-compose-theme-adapter)
 * instead, as it allows much finer-grained reading of your theme.
 *
 * Synthesizing a material theme from an `AppCompat` theme is not perfect, since `Theme.AppCompat`
 * does not expose the same level of customization as `Theme.MaterialComponents`.
 * Going through the pillars of material theming:
 *
 * ### Colors
 *
 * AppCompat has a limited set of top-level color attributes, which means that [AppCompatTheme]
 * has to generate/select alternative colors in certain situations. The mapping is currently:
 *
 * | MaterialTheme color | AppCompat                                             |
 * |---------------------|-------------------------------------------------------|
 * | primary             | colorPrimary                                          |
 * | primaryVariant      | colorPrimaryDark                                      |
 * | onPrimary           | Calculated black/white                                |
 * | secondary           | colorAccent                                           |
 * | secondaryVariant    | colorAccent                                           |
 * | onSecondary         | Calculated black/white                                |
 * | surface             | Default                                               |
 * | onSurface           | android:textColorPrimary, else calculated black/white |
 * | background          | android:colorBackground                               |
 * | onBackground        | android:textColorPrimary, else calculated black/white |
 * | error               | colorError                                            |
 * | onError             | Calculated black/white                                |
 *
 * Where the table says "calculated black/white", this means either black/white, depending on
 * which provides the greatest contrast against the corresponding background color.
 *
 * ### Typography
 *
 * AppCompat does not provide any semantic text appearances (such as headline6, body1, etc), and
 * instead relies on text appearances for specific widgets or use cases. As such, the only thing
 * we read from an AppCompat theme is the default `app:fontFamily` or `android:fontFamily`.
 * For example:
 *
 * ```
 * <style name="Theme.MyApp" parent="Theme.AppCompat">
 *     <item name="fontFamily">@font/my_font</item>
 * </style>
 * ```
 *
 * Compose does not currently support downloadable fonts, so any font referenced from the theme
 * should from your resources. See [here](https://developer.android.com/guide/topics/resources/font-resource)
 * for more information.
 *
 * ### Shape
 *
 * AppCompat has no concept of shape theming, therefore we use the default value from
 * [MaterialTheme.shapes]. If you wish to provide custom values, use the [shapes] parameter.
 *
 * @param context The context to read the theme from.
 * @param readColors whether the read the color palette from the [context]'s theme.
 * @param readTypography whether to read the font family from [context]'s theme.
 * @param shapes A set of shapes to be used by the components in this hierarchy.
 */
@Deprecated(
    """
   AppCompat ThemeAdapter is deprecated.
For more migration information, please visit https://google.github.io/accompanist/themeadapter-appcompat/
"""
)
@Composable
public fun AppCompatTheme(
    context: Context = LocalContext.current,
    readColors: Boolean = true,
    readTypography: Boolean = true,
    shapes: Shapes = MaterialTheme.shapes,
    content: @Composable () -> Unit
) {
    val themeParams = remember(context.theme) {
        context.createAppCompatTheme(
            readColors = readColors,
            readTypography = readTypography
        )
    }

    MaterialTheme(
        colors = themeParams.colors ?: MaterialTheme.colors,
        typography = themeParams.typography ?: MaterialTheme.typography,
        shapes = shapes,
    ) {
        // We update the LocalContentColor to match our onBackground. This allows the default
        // content color to be more appropriate to the theme background
        CompositionLocalProvider(
            LocalContentColor provides MaterialTheme.colors.onBackground,
            content = content
        )
    }
}

/**
 * This class contains some of the individual components of a [MaterialTheme]:
 * [Colors] & [Typography].
 */
@Deprecated(
    """
   AppCompat ThemeAdapter is deprecated.
For more migration information, please visit https://google.github.io/accompanist/themeadapter-appcompat/
"""
)
public data class ThemeParameters(
    val colors: Colors?,
    val typography: Typography?
)

/**
 * This function creates the components of a [androidx.compose.material.MaterialTheme], reading the
 * values from the `Theme.AppCompat` Android theme. Please see the documentation
 * of [AppCompatTheme] for more information on how the theme is read.
 *
 * The individual components of the returned [ThemeParameters] may be `null`, depending on the
 * matching 'read' parameter. For example, if you set [readColors] to `false`,
 * [ThemeParameters.colors] will be null.
 *
 * @param readColors whether the read the color palette from this context's theme.
 * @param readTypography whether to read the font family from this context's theme.
 *
 * @return [ThemeParameters] instance containing the resulting [Colors] and [Typography]
 */

@Deprecated(
    """
   AppCompat ThemeAdapter is deprecated.
For more migration information, please visit https://google.github.io/accompanist/themeadapter-appcompat/
"""
)
public fun Context.createAppCompatTheme(
    readColors: Boolean = true,
    readTypography: Boolean = true
): ThemeParameters = obtainStyledAttributes(R.styleable.ThemeAdapterAppCompatTheme).use { ta ->
    require(ta.hasValue(R.styleable.ThemeAdapterAppCompatTheme_windowActionBar)) {
        "createAppCompatTheme requires the host context's theme to extend Theme.AppCompat"
    }

    val colors = if (readColors) {
        val isLightTheme = ta.getBoolean(R.styleable.ThemeAdapterAppCompatTheme_isLightTheme, true)

        val defaultColors = if (isLightTheme) lightColors() else darkColors()

        /* First we'll read the Material color palette */
        val primary = ta.parseColor(R.styleable.ThemeAdapterAppCompatTheme_colorPrimary)
        // colorPrimaryDark is roughly equivalent to primaryVariant
        val primaryVariant =
            ta.parseColor(R.styleable.ThemeAdapterAppCompatTheme_colorPrimaryDark)
        val onPrimary = primary.calculateOnColor()

        // colorAccent is roughly equivalent to secondary
        val secondary = ta.parseColor(R.styleable.ThemeAdapterAppCompatTheme_colorAccent)
        // We don't have a secondaryVariant, so just use the secondary
        val secondaryVariant = secondary
        val onSecondary = secondary.calculateOnColor()

        // We try and use the android:textColorPrimary value (with forced 100% alpha) for the
        // onSurface and onBackground colors
        val textColorPrimary = ta.parseColor(
            R.styleable.ThemeAdapterAppCompatTheme_android_textColorPrimary
        ).let { color ->
            // We only force the alpha value if it's not Unspecified
            if (color != Color.Unspecified) color.copy(alpha = 1f) else color
        }

        val surface = defaultColors.surface
        val onSurface = surface.calculateOnColorWithTextColorPrimary(textColorPrimary)

        val background =
            ta.parseColor(R.styleable.ThemeAdapterAppCompatTheme_android_colorBackground)
        val onBackground = background.calculateOnColorWithTextColorPrimary(textColorPrimary)

        val error = ta.parseColor(R.styleable.ThemeAdapterAppCompatTheme_colorError)
        val onError = error.calculateOnColor()

        defaultColors.copy(
            primary = primary,
            primaryVariant = primaryVariant,
            onPrimary = onPrimary,
            secondary = secondary,
            secondaryVariant = secondaryVariant,
            onSecondary = onSecondary,
            surface = surface,
            onSurface = onSurface,
            background = background,
            onBackground = onBackground,
            error = error,
            onError = onError
        )
    } else null

    /**
     * Next we'll create a typography instance. We only use the default app:fontFamily or
     * android:fontFamily set in the theme. If neither of these are set, we return null.
     */
    val typography = if (readTypography) {
        val fontFamily = ta.parseFontFamily(R.styleable.ThemeAdapterAppCompatTheme_fontFamily)
            ?: ta.parseFontFamily(R.styleable.ThemeAdapterAppCompatTheme_android_fontFamily)
        fontFamily?.let {
            Typography(defaultFontFamily = it.fontFamily)
        }
    } else null

    ThemeParameters(colors, typography)
}
